Liquid crystal displays (LCDs) are typically applied to notebook personal computers and liquid crystal display televisions. Color filters are essential components of liquid crystal display devices. Pigment dispersion processes are presently the most widely used to produce color filters.
Photosensitive resin compositions suitable for use in the production of color filters by pigment dispersion processes are required to be excellent in terms of smoothness, resolution, developability, heat resistance, light resistance, spectroscopic properties, simplification of the production process, sensitivity and storage stability.
A general fluorene-based polymer is prepared by polycondensation of a diol compound containing a fluorene moiety and an acid dianhydride. A negative-type photosensitive resin composition comprising the fluorene-based polymer has good adhesion to a substrate but is vulnerable to development due to the high acid value and low molecular weight of the fluorene-based polymer.
For better development margin and chemical resistance of the conventional fluorene-based polymer, the equivalent ratio between the diol compound and the acid dianhydride, both of which contain reactive groups, must be close to 1:1. However, a portion of the less soluble acid dianhydride remains unreacted to impair the storage stability of the polymer and becomes a cause of increasing the acid value of the polymer. As a result, a pattern formed using the polymer tends to be peeled off. Meanwhile, the use of the diol compound in a larger amount than the acid dianhydride leads to a decrease in molecular weight as well as in acid value, resulting in poor development margin and chemical resistance of the polymer.